A 47
B 42
C 51
D 54
Correct Answer: Option C
x-1/x=7
=> (x-1/x)2 = 72
=> x2 -2.x.1/x + (1/x)2 = 49
=> x2 + 1/x2 -2 = 49
=> x2 + 1/x2 =49 + 2 =51
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